Family Androstachydaceae

Androstachydaceae Airy Shaw

~ Euphorbiaceae

Habit and leaf form. Trees (poplar-like in habit, with decussate branching); leptocaul. Leaves opposite; petiolate; simple, or compound; when simple, somewhat peltate; when compound, ternate, or palmate (3–7 foliolate); stipulate. Stipules intrapetiolar; concrescent; ochreate (forming an oblong, flattened sheath enclosing the terminal bud).

Stem anatomy. Secondary thickening developing from a conventional cambial ring (?).

Reproductive type, pollination. Plants dioecious. Female flowers without staminodes.

Inflorescence, floral, fruit and seed morphology. Flowers solitary (when female), or aggregated in ‘inflorescences’ (amentiform, cernuous, in shortly pedunculate triads when male); when solitary/female, axillary; in catkins (when male); small; acyclic (male), or cyclic (female). The perianth acyclic and the androecium acyclic (spiralled, in male flowers). Free hypanthium absent. Hypogynous disk absent (in both male and female flowers).

Perianth sepaline; 2–3 (in lateral members of the male triads), or 5 (in the terminal male flower), or 5–6 (in female flowers). Calyx 2–3 (in lateral members of the male triads), or 5 (in the terminal male flower), or 5–6 (in female flowers); polysepalous; more or less imbricate.

Androecium in male flowers 20–100 (?—‘many’, spiralled on an elongated axis). Androecial members free of the perianth; free of one another. Androecium exclusively of fertile stamens. Stamens 20–100 (?—‘many’); polystemonous; filantherous (the filaments very short). Anthers apiculate. Pollen grains aperturate; 4–12 aperturate; (oligo-) foraminate.

Gynoecium in female flower, 3(–5) carpelled. The pistil 3(–5) celled. Gynoecium syncarpous; synstylovarious; superior. Ovary 3(–5) locular. Gynoecium stylate. Styles 3(–5); apical. Stigmas 3(–5). Placentation apical. Ovules 2 per locule; pendulous; non-arillate; crassinucellate.

Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal and loculicidal. Seeds endospermic.

Geography, cytology. Tropical. Southeast tropical Africa, Madagascar.

Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Malviflorae (?); Euphorbiales (?). Cronquist’s Subclass Rosidae; Euphorbiales. APG (1998) Eudicot; core Eudicot; Rosid; Eurosid I. APG 3 (2009) Order: Santalales.

Species 5. Genera 1; only genus, Androstachys.

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